Plant genetic resource: Threats and opportunities arising from climate change

Andy Jarvis, Julián Ramírez, Nora Castañeda, Nigel Maxted, Robert Hijmans and Jacob Van Etten

© Neil Palmer (CIAT)

Content

• Some background on climate change and what it means for agriculture

• Focus on crop wild relatives: threats and opportunities

• The CGIAR-ESSP lead Climate Change, Agriculture and Food Security global program of research

• Concluding remarks

Climate change is not new…but is accelerating

Global Climate Models (GCMs)

• 21 global climate models in the world, based on atmospheric sciences, chemistry, biology, and a touch of astrology

• Run from the past to present to calibrate, then into the future

• Run using different emissions scenarios

Temperatures rise….

Changes in rainfall…

The Impacts on Crop Suitability

Empirical evidence of serious problems in the US

•In many cases, roughly 6-10% yield loss per degree

•For example, US maize, soy, cotton yields fall rapidly when exposed to temperatures >30˚C

Schlenker and Roberts 2009 PNAS

Average change in suitability for all crops in 2050s

Impacts of climate change to food security

• Lobell et al. looked at impacts of climate change on food security

• Cassava clearly highlighted as suffering least among many staples

• Particular opportunities as an alternative crop for southern Africa

Crop wild relatives - The foundation of agriculture

Wild relatives of crops• Include both progenitor species and closely related species of cultivated

crops• Faba beans – 0 wild relatives• Potato – 172 wild relative species• Increasingly useful in breeding, especially for biotic resistance

Photos from Jose Valls, CENARGEN

Why conserve CWR diversity?

• Use: 39% pest resistance; 17% abiotic stress; 13% yield increase

• Citations: 2% <1970; 13% 1970s; 15% 1980s; 32% 1990s; 38% >1999

Use!!

234 papers cited

Maxted and Kell, 2009

Florunner, with no root-knot nematode resistance

COAN, with population density of root-knot nematodes >90% less than in Florunner

Wild relative species

A. batizocoi - 12 germplasm accessions

A. cardenasii - 17 germplasm accessions

A. diogoi - 5 germplasm accessions

Grassy stunt virus in riceResistance from Oryza nivara genes(Barclay 2004)

Potato late blightResistance from Solanum demissun and S. stoloniferumNational potato council (2003)

Nevo and Chen 2010

Adaptation to abiotic stress

Quality traits

Post harvest deterioration - Cassava

Courtesy of Emmanuel Okogbenin

• Value as wild plant species in natural ecosystems

• Value of CWR as actual or potential gene donors:– US$340 million a year in US (Prescott-Allen and

Prescott Allen, 1986)– $20 billion toward increased crop yields per

year in the United States and $115 billion worldwide (Pimentel et al., 1997)

– US$10 billion annually in global wholesale farm values (Phillips and Meilleur, 1998)

Why conserve CWR Diversity?

• Individual examples of use:– Lycopersicon chmielewskii sweetening tomato US $ 5-8million per year

(Iltis, 1988)– Various CWR of wheat provide disease resistance to wheat and US

benefits by US $ 50m per year (Witt, 1985)

Courtesy of Nigel Maxted

Threats

Impact of climate change on CWR• Assessment of shifts in distribution

range under climate change• Wild potatoes• Wild African Vigna• Wild peanuts

Latitudinal and Elevational Shifts

Peanuts• Shift south and upwards

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Latitude

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Current Richness

Future Richness (unlimited dispersal)

Future Richness (no dispersal)

A - Peanut

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Elevation

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Current Richness

Future Richness (unlimited dispersal)

Future Richness (no dispersal)

B - Peanut

Latitudinal and Elevational Shifts

Potatoes• Shift upwards

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Latitude

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Current Richness

Future Richness (unlimited dispersal)

Future Richness (no dispersal)

C - Potato

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Elevation (m)

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Current Richness

Future Richness (unlimited dispersal)

Future Richness (no dispersal)

D - Potato

Summary Impacts

• 16-22% (depending on migration scenario) of these species predicted to go extinct

• Most species losing over 50% of their range size• Wild peanuts were the most affected group, with 24

to 31 of 51 species projected to go extinct • For wild potato, 7 to 13 of 108 species were

predicted to go extinct

Florunner, with no root-knot nematode resistance

COAN, with population density of root-knot nematodes >90% less than in Florunner

Wild relative species

A. batizocoi - 12 germplasm accessions

A. cardenasii - 17 germplasm accessions

A. diogoi - 5 germplasm accessions

SpeciesChange in area

of distribution (%)Predicted state

in 2055

batizocoi -100 Extinctcardenasii -100 Extinctcorrentina -100 Extinctdecora -100 Extinctdiogoi -100 Extinctduranensis -91 Threatenedglandulifera -17 Stablehelodes -100 Extincthoehnii -100 Extinctkempff-mercadoi -69 Near-Threatenedkuhlmannii -100 Extinctmagna -100 Extinctmicrosperma -100 Extinctpalustris -100 Extinctpraecox -100 Extinctstenosperma -86 Threatenedvillosa -51 Near-Threatened

Impact of Climate Change – Wild Peanuts

More immediate threats….

Adapted from Nature, v.466, p.554-556, 2010

Concentration of the natural distribution on the area of most intensive cattle-raising and crop production activity in Brazil has not been a serious problem, in the past, for preservation of local wild species of Arachis, but the advance of the modern, mechanized agriculture, in the last few decades, and specially the use of herbicides have imposed severe pressure on wild populations. This is also true for Eastern Bolivia, where many species of section Arachis occur.

Slide provided by Jose Valls, CENARGEN

Slide provided by Jose Valls, CENARGEN

How well conserved are crop wild relatives?

Gap Analysis

© Neil Palmer (CIAT)

Why Gap Analysis?

• Tool to assess crop and crop wild relative genetic and geographical diversity

• Allows detecting incomplete species collections as well as defining which species should be collected and where these collections should be focused

• Assesses the current extent at which the ex situ conservation system is correctly holding the genetic diversity of a particular genepool

To know what you don’t have, you first need to know what you do have

The visible global system

The Gap Analysis process

Proxy for:

• Range of traits

Proxy for:

• Diversity

• Possibly biotic traits

Proxy for:

• Abiotic traits

• Identifying gaps

An example in Phaseolus

Herbarium versus germplasm: Geographic

Herbarium versus germplasm: Taxon

Conserved ex situ richness versus potential

Priorities: Geographic and taxonomic

Gap Analysis

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Taxon-level and genepool level priorities

Wild Vigna collecting priorities

• Spatial analysis on current conserved materials

• *Gaps* in current collections

• Definition and prioritisation of collecting areas

• 8 100x100km cells to complete collections of 23 wild Vigna priority species

Exploration and ex-situ conservation of Capsicum flexuosum

• Uncommon species of wild chilli, found in Paraguay and Argentina

• 18 known registers of the plant

• 2 germplasm accessions conserved in the USDA

• Genetically unknown

• Found in an area undergoing high levels of habitat loss

Capsicum flexuosum - FloraMap

Habitat: Forest Margins

Road Access

Priority Areas for Collection

Results

• 6 new collections of C. flexuosum

• 160 seeds conserved ex situ

• One plant found with few seeds, where previous herbarium record

• First accession conserved ex situ 1998

2001

2002

• 1 plant found, with few seeds

Using GIS model

Climate Change, Agriculture and Food Security: A major new global

program to rise to the challenge

Climate Variability and Change

ImprovedEnvironmental

Benefits

ImprovedLivelihoods

ImprovedFood Security

Current agricultural,NRM & food systems

Adapted agricultural,NRM & food systems

Trade-offs and synergies

4. Diagnosis and vulnerability assessment for making strategic choices

1. Adaptation for confronting climate risk

2. Adaptation for progressive climate change

3. Mitigation for reducing GHG emissions, enhancing carbon-storage and reducing poverty

Theme Objective

1. Adaptation to Progressive Climate Change

1.1 Adapted farming systems to changing climate conditions 1.2 Breeding strategies for future climatic conditions1.3 Species and genetic diversity for climate change

Major research questions to be addressed:

1. What priority genepools for climate change adaptation are threatened, and how can they be conserved to ensure their continuing availability?

2. How do cultural practices exploit this diversity and how can farmers’ knowledge be used to help identify landraces and crop varieties suited for specific climatic conditions?

3. How can access to crop diversity local farmers be facilitated through enhanced seed systems or other mechanisms?

4. How does on farm crop diversity in production systems contribute to maintaining productivity in the face of progressive climate change and increased variability in climate?

Conclusions

• Major challenges from climate change: can agriculture stand up to a 2 degree warmer world?

• Plant genetic resources threatened by climate change, but also a key element of the solution

• Crop wild relative use on the increase, but poorly conserved ex situ and under threat in situ

• Need for a major collecting effort to fill gaps, and explore novel genetic approaches to further stimulate their use

a.jarvis@cgiar.org